In general, it should be compatible with 2010.2 repositories. And we try to make updates as easy as possible. There should be no problems with installing 2010.2 and updating it from MIB 2010.3 repository. And no problems with installing packages from 2010.2 updates & backports.

There are no installation ISOs yet. But we have plans to release them one day.

2010.3 is not really a fork. We don't plan to support it forever. And we don't have infrastructure and manpower for that. Our goal is to keep 2010.2 as much up to date as possible but without sacrificing its stability.